The company decided not to start the study.

The objective of the registry study is to demonstrate the clinical utility of the CELLSEARCH® CTC Test among the Medicare-Eligible metastatic Breast Cancer (mBC) patients in the United States. The objective of the present registry is to demonstrate the impact on patient management of the CELLSEARCH® CTC Test among the Medicare-eligible mBC patients. Hereto the hypothesis that the availability of CTC information provides clinicians important, timely information and impacts treatment decisions, will be tested.

This study is IDE-exempt since CELLSEARCH® CTC Test is a legally marketed device in the US, and is being used in accordance with its labeling.

Inclusion Criteria:

Patient has documented (histologically/pathologically confirmed) mBC diagnosis

• Patient is at least 65 years of age at time of mBC diagnosis
• Patient is male or female
• Patient is being actively treated at the cancer center by a physician who uses or plans to use CTC testing on his mBC patients at lease every quarter.

Exclusion Criteria:

• Patients breast cancer is secondary not primary

"Cases" of CTC-tested mBC patients being cared for by physicians who routinely (i.e., test at least once every quarter) incorporate CTC testing in their management of mBC patients.